Trans - Radial Styloid , Trans - Scaphoid , Trans - Triquetral Perilunate

SUMMARY: A rare case of trans-radial styloid, trans-scaphoid. trans-triquetral perilunate dislocation is described. The injury was treated by reduction and internal fixation using a Herbert screw and Kirschner wire. A good functional result was achieved. A review of the literature illustrates that early surgery is recommended. Alternative su rgical approaches are discussed. Case Report A twenty-one year old factory worker fell from his motorcycle, landing on his outstretched left hand. On arrival in the casualty department the left wrist was tender and deformed, with parasthesiae in the median nerve distribution. Radiographic examination revealed a dorsal perilunate dislocation with associated fractures of the scaphoid, radial styloid and triquetrum (Fig I). That day, under a general anaesthetic, the perilunate dis-location was reduced by gentle distraction and palmar flexion of the wrlst while maintaining thumb pressure on the lunate from the volar surface. The scaphoid fracLUre was then reduced and internally fixed with a Herbert screw (I) through a Russe approach (2) and the radial styloid reduced and fixed with a percutaneous K-wire (Fig 2). Screening under image intensification suggested that the wrist was stable in slight nexion so it was im-mobilised in that position in a forearm cast for six weeks. The K-wire and cast were removed after six weeks and the wrist mobilised. One year post injury the fractures of the scaphoid and radial styloid had united. The proximal fragment of the scaphoid appeared relatively dense. The avulsion fragment of the triquetrum remained un-united (Fig 3). There was no evidence of carpal instability on stress views of the wrist although the Herbert screw appeared rather vertical lO the lunate suggesting some palmar flexion of the scaphoid. The median nerve parasthesiae had recovered. The patient had no wrist discomfort and had returned to work. There was slight restriction of ulnar deviation, with 50 degrees of dorsiflexion and 65 degrees of palmar flexion. Grip strength was measured at 200mmHg compared with 260mmHg on the right. Using Green and O'Brien's method of evaluation (3,4), our patient had good wrist function with a wrist score of 85 (good = 75-90). Discussion Mayfield and Johnson (5) described the mechanism o f injury in perilunate fracture-dislocation as forcible wrist extension, ulnar deviation and intercarpal supination. They defined four stages of progressive peri lunar insta-bi lity with increasing levels of instability as the injury progressed through the greater arc, from the radial styloid, through the scaphoid, capitate and …